I worked in the Grand Kankakee Marsh County Park for over three months before I finally saw the infamous family of river otters that had made a home sixty yards away from one of the park’s duck blinds.

Notice I say infamous, not famous.   

When people think of river otters, they think playful puppy of the sea. Energetic, enthusiastic, torpedoing back and forth in acrobatic circles. Or hopping above ground with tiny, hurried steps toward prey (You might think urchins on the belly, but that would be a sea otter, not a river otter). Those images are all true and all practice for one thing only: killin’. 

That combination of skills makes them remarkably talented predators.  River otters were born to kill. Like several species, including house cats, river otters sometimes kill no apparent reason, especially if the food is plentiful and weather tolerable. Their extra energy is spent playing with one another in North America’s rivers, but also in tearing the shell from a snapping turtle, gouging out an alligator’s belly, or pouncing on a molting duck.

Several studies have also clearly demonstrated inter- and intra-species homicidal-rape and necrophilia are common among sea otters. Of course, river otters are a different species, and have not been subjected to the same studied scrutiny, but biologists are fairly confident this behavior is shared to some degree.

And attacks against their only natural predator—humans—aren’t uncommon either. In one recent case, a pack of 20 otters attacked a Singapore man, biting him 26 times in 10 seconds.

River otters represent one of the most fundamental questions in modern conservation: is returning a native species to its historical territory always a good idea?

In this case, the fur trade, along with a loss of habitat and pollution, decimated the river otter population until the 1970s, when efforts to reintroduce the species began.  At that time eleven states had no river otters, and nine additional states had minuscule populations.  Repopulation efforts have been very successful, even prompting a return to trapping the species for its prized fur (the densest of all fur-trade mammals). 

This return to its native lands has had a cost. In some locations, nature was able to “close the gap” over decades and maintain equilibrium without the presence of the predatory otter.  Simply bringing them back into the mix upset this adapted balance. Most of the otters’ chief predators, save foxes and coyotes, have also vanished from many waterways, giving this voracious species an unnatural advantage.

Conservationists must ask themselves serious questions in relation to the river otter and other reintroduced species: Is the primary task of conservation a return to a previous natural state before human intervention; or, is it to maintain the current, sustainable balance of nature?

If you come across river otters, observe, enjoy, but KEEP YOUR DISTANCE.

Want to Know More?

Here’s a thorough article from the Smithsonian National Zoo on the North American River Otter. About as concise and well-informed as you can get.

The US Forest Service released this fantastic study on conservation effects, efforts and strategies for the North American River Otter.

Here’s the 2010 paper from the California Department of Fish and Game “Lesions and Behavior Associated with Forced Copulation of Juvenile Pacific Harbor Seals (Phoca vitulina richardsi) by Southern Sea Otters (Enhydra lutris nereis).”